Questions and Answers Section 3

Questions and Answers

Question :

21.Monel metal contains

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68% nickel, 29% copper and 3% other constituents.

Note:-

Monel is a group of nickel alloys, primarily composed of nickel and copper, with small amounts of iron, manganese, carbon, and silicon.

Question :

22.The process which improves the machinability of steels, but lowers the hardness and tensile strength, is

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Spheroidising.

Note:-

Spheroidising is an annealing treatment for. improving cold formability and machinability of steels.

Question :

23.Which of the following iron exists at 910° C?

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α-iron.

Note:-

The alpha iron (α) is a body-centered cubic (BCC) and the gamma iron (γ) is a face-centered cubic (FCC).

Question :

24.The iron ore mostly used for the production of pig iron is

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Hematite.

Note:-

 Hematite, also spelled as hematite, is the mineral form of iron(III) oxide, one of several iron oxides. It is the oldest known iron oxide mineral and is widespread in rocks and soils.

Mohs scale hardness: 5.5–6.5.

Question :

25.A carbon steel having Brinell hardness number 100 should have ultimate tensile strength closer to

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350 N/mm2.

Note:-

BHN is designated by the most commonly used test standards (ASTM E10-14 and ISO 6506–1:2005) as HBW (H from hardness, B from Brinell and W from the material of the indenter, tungsten (wolfram) carbide). In former standards HB or HBS were used to refer to measurements made with steel indenters.

Question :

26.The steel widely used for making precision measuring instruments is

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nickel steel.

Note:-

nickel steel is a type of stainless steel containing chromium and nickel.

Question :

27.The high speed steel has maximum percentage of

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tungsten.

Note:-

High Speed Steels are high-performance special steels offering high hardness at temperatures up to 500°C and high wear resistance, thanks to alloying elements like tungsten, molybdenum, vanadium and chromium which are able to form carbides. To improve hot hardness, cobalt may also be added.

Question :

28.The approximate height of a blast furnace is

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30 m.

Note:-

A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally pig iron, but also others such as lead or copper. Blast refers to the combustion air being "forced" or supplied above atmospheric pressure.

Question :

29.A steel alloy containing 36% nickel is called 

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Invar.

Note:-

Invar, also known generically as FeNi36, is a nickel–iron alloy notable for its uniquely low coefficient of thermal expansion.

Question :

30.The process of inducing carbon to low carbon steels in order to give it a hard surface is known as

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carburising.

Note:-

Into Carburising process add carbon to (iron or steel), in particular by heating in the presence of carbon to harden the surface.